Pump



Sept, 25, 1955 c. o. GLASGOW PUMP 5 Sheets--SheerI 1 Filed June 3, 1964 sept. 28, 1965 C. O. GLASGUW PUMP Filed June 3, 1964 5 Sheets-Sheet 2 FLE-2 INVENTOR.

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IN VEN TOR. CLAef-/vc 0.. 62456014/ BY @We ,fd ATTOQA/-YS' United States Patent Office 3,298,388 Patented Sept. 28, 1965 PUMP k 'I' l Okl Clarence 0. Glasgow 2620 S. Yor town, u sa, a. Filed June 3, 1964, ser. No. 372,259 14 Claims. (Cl. 103--57) This invention relates generally to improvements in positive displacement pumps. More particularly, butnot by way of limitation, this invention relates to a positive displacement pump which includes at least two reciprocating pistons or plungers driven by rotating screws.

For some time there has been a n eed. for a pump capable of accurately and positively delivering a constant volume of fluid. For example, such a pumphas been needed to accurately meter and inject additives intosoap, gasoline, water and various other chemical compositions. More specifically, in the soap making. industry, perfumes are added to soaps to provide a distinctive odor. Such perfumes may be rela-tively expensive and 1t is necessary to accurately control the quantity of perfume added. Also, chemicals such as flourine are often added to municipal water supplies and the injection of an excess of such chemicals may be harmful as well as expensive, therelfore the quantity injected must be carefully controlled.

More recently, certain developments 1n the. surgical field, such as open heart surgery, have clearly indicated the need for a pump that is quiet in operation and capable of delivering a specified volume of uid constantly and with great accuracy. Clearly, such pumps would also aid greatly in medical treatments wherein the. blood must be completely replaced. A pump which is quiet in operation is also highly desirable where the medical treatment of a patient requires a slow, constant injection of liquid food or other treating chemical into the bloodstream.

Positive displacement pumps having a pair of reciprocating pistons driven by rotating screws have been constructed in the past. In some instances, these pumps have incorporated rotating screws that are rotatably mounted in and reciprocate with the pistons. In other instances, the screws rotate relative to the pistons but do not reciprocate therewith. Almost without exception, such pumps have incorporated some form of mechanical clutch or transmission disposed between the screws and the means rotating the screws to accomplish a reversal in rotation of the screws and the consequent reversal in the direction of reciprocation of the pistons. The use of a mechanical clutch or transmission in an attempt to 1nstantaneously effect a reversal of the screws and pistons invariably introduces a slowing down, stopping during reversal and speeding up of the pump mechanism. The occurrence of such a speed variation, for even a relatively short period, will result in a surge or change in the displaced volume. The surges thus produced, while not critical in some oper-ating environments, are undesirable and may result in serious damage in some of the applications previously mentioned.

There has also been a need for a pump that will accurately deliver a specified volume of iluid and that is provided with a means for simultaneously extracting a small but proportional quantity of the fluid moved by the pump. One application for such a pump is in a system utilized to transfer oil from lease tanks to pipe lines for delivery to refineries. Presently, transfer systems are provided with a pump to move the oil, a separate meter for determining the amount of oil delivered, and a sampling mechanism for extracting a portion of the oil for qualitative analysis. As is well known, the production of oil is a highly competitive enterpise and any means of either eliminating equipment or increasing the efliciency of operation of existing equipment is very desirable,

This invention contemplates a pump having a pair of reciprocating pistons positioned in a pair of cylinders in a pump housing. The pistons are driven 'by a pair of rotating screws. The pump includes means for translating the rotational movement of the screws into reciprocating movement of the pistons. The screws are: rotated by a motor which has the characteristics of rotating at a constant speed and of being instantaneously reversible to reverse the direction of rotation of the rscrews and, corisequently, reverse the direction of reciprocation of the pistons.

In one aspect, this invention contemplates the arrangement of the aforesaid pump so that the pistons will reciproca-te in relatively opposite directions, whereby the pump will have a constant output volume..

ln another aspect, this invention contemplates the arrangement of the aforesaid pump so that 4the pistons will reciprocate in the same relative direction and be provided with an independent valve mechanism for each cylinder having a common inlet andseparate outlets, whereby one of the pistons may be utilized to sample a portion of the iluid pumped.

Accordingly, one object of this invention is to provide an improved reciprocating piston pump that is capable of delivering a constant volume of iluid.

Another object of the invention is to provide an improved pump that is quiet in operation.

A further object of the invention is to provide an irnproved reciprocating piston pump that is quiet in operation and capable of delivering a constant volume of fluid.

Still another object of the invention is to provide an improved pump that utilizes rotating screws t-o drive reciprocating pistons.

A still further object of the invention is to provide r an improved reciprocating piston pump that occupies a minimum of space.

Another object of the invention is to provide an improved reciprocating piston pump that utilizes one piston for pumping a fluid and the other piston to simultaneously provide a proportional sample of the iluid pumped.

One other object of the invention is to provide an improved pump that is relatively simple and inexpensive to manufacture.

` The foregoing and additional objects and advantages of the invention will become more apparent as the following description is read in conjunction with the accompanying drawings wherein like reference characters denote like parts in all views, and wherein:

FIG. l is a side elevation view, partly in section, illustrating a pump constructed in accordance with the invention.

FIG. 2 is a cross-sectional View taken along a line 2-2 of FIG. l, but showing the motor in elevation;

FIG. 3 is an end elevation view of the pump of FIG. l;

FIG. 4 is an enlarged cross-sectional View of the valve mechanism associated with one of the cylinders and taken along a line 4 4 of FIG. 2;

FIG. 5 is a view similar other embodiment of a with the invention; and,

FIG. 6 is an end elevation View of the pump of FIG. 5.

Referring to the drawings, and to FIGS. l, 2 and 3 in particular, shown therein is a pump assembly constructed in accordance with the invention and generally designated by the reference character 10. The pump 10 includes a cylinder head, or housing 12 which is secured to a longitudinally extending support` member ll4` by a pair of cap screws lo. As shown most clearly in FIG. 2, the housing l2 includes a pair of longitudinally extending bores or cylinders 18 and 20. A pair of piston assemblies 22 and 24 are disposed for reciprocating movement in the cylinders 18 and 20, respectively. Each of to FIG. 2, but showing aripump constructed in accordance the piston assemblies 22 and 24 is provided with a sealing member 26 attached to the end thereof by a screw 28. The sealing members 26 are arranged to sealingly engage the inner wall of the cylinders 18 and 20 to prevent the leakage of uid thereby during the operation of the pump 10. Ball nuts 38 and 32 are attached to the opposite ends of the piston assemblies 22 and 24, respectively, and are axially aligned with a bore 34 in the piston assembly 22 and a bore 36 in the piston assembly 24.

A rotatable shaft 38 has one end extending through a bearing 42 which is mounted in a support plate 40. The shaft 38 is threaded as shown at 44 to mate with the ball nut 30. The threads 44 on the shaft 38 extend through the ball nut 30 into the bore 34 in the piston assembly 22. Similarly, a shaft 46 has one end extending through and rotatably mounted in a bearing 48 in the support plate 40. The shaft 46 is threaded at 50 and the threaded portion thereof extends through the ball nut 32 into the bore 36 in the piston assembly 24. The support plate 40 is rigidly attached to the longitudinal supporting member 14 by means of screws 52. The threads 44 on the shaft 38 and the threads 50 on the shaft 46 are arranged to mate with the ball nuts 30 and 32, respectively, so that rotation of the shafts 38 and 46 in their respective bearings 42 and 48 will cause the piston assemblies 22 and 24 to move into or out of the cylinders 18 and 20, depending upon the direction of rotation of the shafts 38 and 46. The end of the shaft 38 extending through the supporting plate 40 is provided with a spur gear 54 and a cog-type pulley 56. The end of the shaft 46 extending through the support plate 40 is provided with a spur gear 58 which meshes with the spur gear 54 whereby the shafts 38 and 46 will be caused to rotate in relatively opposite directions upon the rotation of either shaft 38 or 46.

As may be more clearly seen in FIG. 3, a cog-type belt 60 extends from the pulley 56 over a cog-type pulley 62 which is mounted on the shaft of an electric motor 64. Cog-type belts are illustrated and are preferred because of their ability to transmit torque without slipping. They are also extremely quite in operation as compared with a comparable positive drive made up of chains and sprockets.

The electric motor 64 is preferably of the synchronous type so that it will operate at a constant speed. The motor 64 should also have the characteristic of running at extremely slow speeds without gearing and be able to stop, start and reverse almost instantaneously. The motor 64 is connected with a source of electrical energy as indicated at 66 by a conductor 68, and with a switch 70 by conductors 72 and 74. The switch 70 is also connected by a conductor 76 with the source of electrical energy 66. The switch 70 is of the two-position type so that when an actuating lever 78 which is pivotally mounted thereon is depressed, a circuit will be completed with the motor 64 through the conductor 72, causing the motor 64 to reverse its direction of rotation.

The switch 70 is mounted in such a position that it will be actuated by a switch rod 80 which is slidingly mounted in the support plate 40 and in a block 82 which is attached to the longitudinal support member 14 by screws 84. A pair of lugs or projections 86 and 88 extend up- Wardly from the switch rod 80 and are adapted to be engaged by the ball nut 32 mounted on the piston assembly 24. A screw 98, which may have a nylon tip, extends into the block 82 to frictionally engage the switch rod 80 so that some force will be required to move the rod 80. The purpose of providing the frictional engagement of the screw 90 with the rod 80 is to assure that Vibrations occurring in the pump will not cause the rod 80 to shift inadvertently.

A pump valve assembly 92 is attached to the pump housing 12 by a plurality of screws 94. A gasket 96 is located between the end of the pump housing 12 and the valve assembly 92 to prevent the leakage of fluid therebetween (see FIG. 4). The valve assembly 92 includes a valve body 98 which is provided with a pair of vertically extending bores 100. As shown most clearly in FIG. 4 (only one bore 100 is illustrated) the bores 100 are threaded at each end to receive an upper valve retaining member 102 and a lower valve retaining member 104. A pair of O-rings 106 and 108 are disposed between each of the valve retaining members 102 and 104, and the valve body 98 to prevent the leakage of fluid from within the valve body 98.

An outlet valve seat 110 is disposed between the lower end of the upper valve retaining member 102 and a valve spacer 112. An inlet valve seat 114 is disposed between the upper end of the lower valve retaining member 104 and the lower end of the spacer member 112.

It can be appreciated from observation of FIG. 4 that the outlet valve seat 110 and the inlet valve seat 114 are identical in all respects. Each of the seats 110 and 114 is provided with a frusto-conical inner surface 116 and 118, respectively, which provides a seat for valve balls 120 and 122. The balls 120 and 122 are disposed in passageways 121 and 123 in the outlet valve seat 110 and inlet valve seat 114, respectively. Fluid communication between the passageways 121 and 123 and the cylinder 20 is provided by a port 124 which extends through the valve body 98 and a plurality of ports 126 in the spacer member 112. Similar Huid passages are provided in the bore 100 which is associated with the cylinder 18. A spring 128 is positioned in a bore 130 provided in the upper valve retaining member 102, and has its lower end in engagement with the valve ball 120 to resiliently retain the ball 120 on the valve seat 110. Ports 131 extend through the wall of the upper valve retaining member 102 and provide fluid communication between the bore 130 and the pump discharge port 132 (see FIG. 1). The lower valve retaining member 104 is similarly provided with a bore 134 having ports 136 extending through the wall thereof providing communication from the bore 134 into an inlet 138 (see FIG. 1).

Communication between the discharge valve mechanisms is provided by bores 140, as indicated by the dash lines in FIG. 2. Stated in another way, the outlets from the valves associated with the cylinders 18 and 20 are manifolded together so that a single discharge outlet 132 is provided in the pump 10. Likewise, the inlet valve mechanisms associated with the cylinders 18 and 20 are manifolded together so that a single inlet 138 is provided in the pump 10. The valve assembly 92 includes the identical valve mechanisms as described in each of the vertical bores 100 therein.

Having described in detail the structure of the embodiment of the pump as shown in FIG. l, the operation thereof will now be described. Assuming that the motor 64 is connected with the source of electrical energy 66, and that the pulley 62 is rotating in a clockwise direction as Shown by the arrows of FIG. 3, the pulley 56 on the shaft 38 will be rotating in the same direction due to its connection to the pulley 62 by means of the cog-type belt 60. The spur gear 54 attached to the shaft 38 will also be rotating in the clockwise direction. The spur gear 58, which is in mesh with the gear 54, and the shaft 46 to which it is attached will rotate in a counterclockwise direction, or in the reverse direction to the rotation of the spur gear 54. Due to the arrangement of the threads 44 on the shaft 38, the ball nut 30 will be moved along the shaft 38 toward the support plate 40. Movement of the ball nut 30 in this direction withdraws the piston assembly 22 from the cylinder 18. Simultaneously, counterclockwise rotation of the shaft 46 with the threads 50 thereon in engagement with the ball nut 32 will cause the ball nut 32 to move toward the cylinder housing 12 and thereby move the piston assembly 24 into the cylinder 20.

As the piston assembly 22 is withdrawn from the cylinder 18, the valve ball 122 is lifted off the seat 114, permitting fluid to flow from the inlet 138 through the ports 136 in the lower valve retaining member 104, through the passageway 123, and through the ports 126 in the spacer member 112 into the cylinder 18. Simultaneously, fluid will be driven from the cylinder 20 through the port 124 in the valve body 98 and into the spacer member 112 associated with the Icylinder 20, lifting t-he valve ball 120 olf the seat 110 and compressing the spring 128 so the fluid can flow therethrough into the ports 131 in the upper valveretaining member 102 and thence through the outlet port 132 into the discharge line (not shown).

Movement of the piston assemblies 22 and 24 in the directions described will continue until the ball nut 32 on the piston assembly 24 comes into engagement with the lug 86 carried by the switch rod 80. Upon engagement between the ball nut 32 and the lug 86, the switch rod 80 will be moved relatively away from the switch 70. Releasing the switch actuating lever 78 reverses the ow of current to the motor 64 and thereby reverses the direction of rotation of the motor 64.

As previously pointed out, the motor 64 is of the type that is instantaneously reversible so that no surge occurs during the transition in direction of movement of the piston assemblies 22 and 24. Reversing the direction of rotation of the motor 64 will reverse the direction of rotation of the shafts 38 and 46 and, consequently, cause the piston assemblies 22 and 24 to move in relatively opposite directions to those previously described. With the motor pulley 62 rotating in a counterclockwise direction, the piston assembly 24 will be moved relatively away from the valve assembly 92 and the piston assembly 22 will be moved relatively toward the valve assembly 92. Movement in this direction will continue until the ball nut 32 on the piston assembly 24 engages the lug 88 carried by the switch rod 80. Upon engagement between the ball nut 32 and the lug 88, the switch rod 80 will be moved into engagement with the switch actuating lever 78 which will again cause the current to the motor 64 to be reversed. As a result of the reversal of the direction of rotation of the motor 64, the piston assemblies 22 and 24 will reverse their direction of movement. The operation of the pump will continue as described until current is no longer supplied to the motor 64.

It should be pointed out that even though the fluid is discharged alternately from the cylinders 18 and 20, no surges occur in the pump due to the constant velocity of the piston assemblies 22 and 24 as they move into and out of the cylinders 18 and 20, and the instantaneous change in direction of movement of the piston assemblies. The constant volume is attainable in the pump due to the use of the synchronous motor 64 which rotates at a constant speed and is capable of instantaneously reversing its direction of rotation. It should also be pointed out that the ball nuts 30 and 32 operating in conjunction with the shafts 38 and 46 provide a very quiet and efcient means for translating rotational movement of the shafts into a linear movement of the piston assemblies 22 and 24. As is well known, cog-type belts, such as the belt 60, provide an excellent means of positively transmitting a drive from one Irotating shaft to another and at the same time providing a drive that is very quiet as compared to the usual chain drive systems. To further enhance the quietness of operation of the pump 10, the spur gears 54 and 58 may be constructed from dissimilar materials. For example, the gear 54 may be constructed from stainless steel, while the gear 58 meshing therewith may be constructed from nylon or a laminated plastic material.

FIGS. 5 and 6 illustrate a different embodiment of a pump, also constructed in accordance with the invention, and generally designated by the reference character 200. The pump 200 includes a cylinder housing 202 which consists of a tubular member 206, which forms a cylinder 208, and a tubular member 210, which forms a cylinder 212, positioned between a pair of spaced-apart parallel plates 214 and 216. A third plate 218 is arranged in parallel spaced relationship to the plate 216. The plates 214, 216 and 218 are retained in their relative positions by means of threaded stay bolts 220 which extend therethrough. The relationship of the plates 214 and 216 is determined by the length of the tubular member 206. A plurality of threaded nuts 222 cooperate with the stay bolts 220 to retain the plates 216 against the end of the tubular member 206. The plate 218 is retained on the stay bolts 220 by means of a plurality of threaded nuts 224 which are disposed on either side of the plate 218 and threadedly engaged with the stay bolts 220.

A piston assembly 226 extends through the plate 216 into the cylinder 208 and carries at one end thereof a sealing member 228 which sealingly and slidingly engages the inner surface of the tubular member 206. The other end of the piston assembly 226 is provided with a ball nut 230. A rotatable shaft 232 has threads 234 thereon and extends through the ball nut 230 in mating relation therewith. The shaft 232 also extends through the plate 218 and is rotatably journaled therein. The piston assembly 226 is in all respects similar to the piston assembly 22 as described in connection with FIGS. l and 2, and functions in an identical manner.

A piston assembly 236 extends through the plate 216 into the cylinder 212 and carries, on the end disposed in the cylinder 212, a sealing member 238 which slidingly and sealing engages the inner wall of the tubular member 210. A ball nut 240 is disposed on the opposite end of the piston assembly 236 and is operably engaged with a shaft 242 having threads 244 thereon. The shaft 242 extends through the plate 218 wherein it is rotatably journaled. The piston assembly 236 is in all respects similar to the piston assemblies 22 or 24 of the pump 10 as described in connection with FIGS. l and 2.

The end of the shaft 232 extending through the plate 218 is suciently long to accommodate a pair of cog-type pulleys 246 and 248. A cog-type pulley 250 is mounted on the extended end of the shaft 242. A cog-type belt 252 extends between the pulleys 248 and 250, so that the shaft 242 will rotate in the same direction as the shaft 232. A cog-type belt 254 extends between the cog-type pulley 246, mounted on the shaft 232, and a cog-type pulley 256, mounted on the shaft of a motor 258. The motor is in all respects identical to the motor 64 described in connection with FIGS. 1 and 2.

A conductor 260 connects the motor 258 with a source of electrical energy 262. The motor 258 is also connected With a two-position switch 264 by conductors 266 and 268. The switch 264 is connected with the source of electrical energy 262 by a conductor 270. The switch 264 is identical to the switch 70 described in connection with the pump 10, and includes a switch actuating lever 272 which is engagable with a slidably mounted switcli rod 274. The switch rod 274 carries a pair of lugs 276 and 278 which are engagable with the ball nut 230 to move the switch actuating lever 272 from one position to the other as described in connection with the operation of the switch rod of the pump 10.

It should be understood that the plate 214 could be constructed similarly to valve assembly 92 and contain the inlet and outlet valves therein. The valve mechanism of the pump 200 has been shown schematically in FIG. 5, and includes an inlet check valve 280 and an outlet check valve 282, each being operably associated with the cylinder 212. The valve mechanism also includes an inlet check valve 284 and an outlet check valve 286, each being connected with the cylinder 208. It can be seen in FIG.

5 that the inlet check valves 280 and 284 are each connected with a common inlet line 288. The outlet check valve 286 is connected with a discharge line 290. As illustrated in FIG. 5, a discharge line 292 extending from the outlet check valve 282 is connected with a sample container 294. Fluid may be removed from the sample 7 container 294 through line 296 by actuation of a valve 298 when required or desired.

The pump 200 is preferably provided with a counter 300. The counter 300 is actuated by linkage 302 which is pivotally mounted on the plate 216. One arm of the linkage 302 extends to a position where it will be engaged by the ball nut 230 to actuate the counter 300 each time the piston assembly 226 makes a stroke. It should be pointed out that the counter 300 can be arranged to count strokes or to indicate the volume pumped by the piston assembly 226.

The pump 200 is illustrated as being arranged for use in connection with the automatic transfer of oil from a lease tank (not shown) to a pipe line (not shown). The inlet line 288 is connected with the lease tank which contains oil pumped from the ground, and the discharge line 290 is connected into the pipe line. The piston assembly 236 is utilized to collect a proportional sample of the fluid being pumped Iby the piston assembly 226.

While the pump 200 operates generally as does the pump 10, it should be pointed out that the arrangement of the belt drive provides for the rotation of the shafts 232 and 242 in the same direction instead of in relatively opposite directions as is true of the shafts 38 and 46 of the pump 10. With the shafts 232 and 242 rotating in the same direction, the piston assemblies 226 and 236 will likewise be moving in the same relative direction.

If the shafts 232 and 242 are rotated in a clockwise direction, as indicated by the arrows of FIG. 6, the piston assembly 226 and the piston iassembly 236 move away from the plate 214 mechanism, thereby drawing Huid from the inlet line 288 through the inlet valves 280 and 284 into the respective cylinders 212 and 208. When the ball nut 230 engages the lug 278 on the switch rod 274, the switch rod 274 will be moved to actuate the switch 264, reversing the direction of rotation of the motor 258 and of the shafts 232 Iand 242.

Upon the reversal of the motor 258, the piston assemblies 226 and 236 will immediately begin moving relatively toward the plate 214 and discharging uid from the cylinder 208 through the outlet valve 286 into the discharge line 290. Simultaneously, uid will be discharged from the cylinder 212 through the outlet valve 282 into the discharge line 292 into the sample container 294 wherein the fluid sample will be collected.

Upon reaching the end of the discharge stroke of the piston assembly 226, the ball nut 230 engages the linkage 302, actuating the counter 300 to indicate that one stroke has been made or to indicate the volume of fluid which has been displaced. Also, the ball nut 230 will engage the lug 276 on the switch rod 274 to move the switch rod 274 away from the switch 264 to reverse the direction of rotation of the motor 258. It can be seen from the foregoing that each time the piston assembly 226 moves forward to discharge fluid into the discharge line 290, the piston assembly 236 will likewise move to discharge fluid from the cylinder 212 into the sample container 294.

The ratio of the sample as compared to the amount of fluid discharged from the cylinder 208 may be varied by changing the ratios between the various pulleys or the relative size of the cylinders 208 and 212. The ratio may also be changed by varying the pitch of the ball nuts and their mating threads 234 and 244 on the shafts 232 yand 242.

If desired, the sample container 294 can be provided with a set of graduations 304 which can be calibrated to indicate the total volume of uid pumped by the cylinder 208. With this arrangement, a check may be made between the sample in the container 294 and the indicated volume shown by the counter 300. Periodically, the sample will be removed from the sample container 294 by opening the valve 298 so that the fluid being pumped can be qualitatively analyzed.

Another use of the pump 200 is to check existing meters installed in lease transfer systems. In such use, the discharge line 290 is tied in to the upstream side of a meter (not shown) and the inlet line 288 is tied to the outlet pipe (not shown) from the lease tanks. The pump 200 is then actuated for a period of time and the volumetric calibration of the counter 300 compared with the volume as indicated by the meter. In this instance also, a double check can be made on the quantity of fluid pumped if the sample container 294 is provided with a set of graduations 304 calibrated to indicate the volume of fluid pumped through the cylinder 208.

In either embodiment of the pump, i.e., either the pump 10 or the pump 200, the ends of the cylinders surrounding the piston assemblies can be left open so that any uid leaking by the sealing members 26, 228 or 238 can be immediately detected visually. Also, each pump incorporates the advantages of the constant speed synchronous motor and preferably the positive drive of the cog-type belts. Furthermore, pumps constructed in accordance with this invention provide highly accurate, yet relatively inexpensive, positive displacement pumps. In the case of the pump constructed in accordance with the embodiment shown in FIGS. l and 2, therein is provided a highly accurate constant volume pump which, even though of the reciprocating piston type, will not have the surges usually lassociated with such pumps. In the case of the embodiment illustrated in FIGS. 5 and 6, therein is provided an accurate positive displacement pump having incorporated therein a means of simultaneously extracting a sample of the fluid being pumped in direct proportion to the quantity of fluid pumped thereby.

It should be understood that the foregoing described embodiments are by way of example only and that many changes and modications can be made therein without departing from the spirit of the invention or from the scope of the annexed claims.

What is claimed is:

1. In a pump:

ahousing having a pair of spaced cylinders therein;

p1ston means operably disposed in each of said cylinders and including:

a piston reciprocably disposed in each of said cylinders; and

a ball nut mounted on an end of each of said pistons;

a pair of rotatable shafts each axially aligned with each of sald pistons and having a threaded portion thereon operably engaging the ball nut of the respective piston whereby said ball nuts and pistons are caused to move in a linear direction in response to rotation of the respective rotatable shaft;

power means for driving said rotatable shafts at a constarrt rotational speed and being further characterized as instantaneously reversible;

connecting means for rotatably connecting said power means with at least one of said shafts; and

switch means operably engaged with at least one of said p1ston means and connected with said power means, whereby said power means is caused to rotate said driving means in one direction and then the other.

2. In the pump of claim 1 wherein said switch means includes:

a rod positioned in said housing for longitudinal movement therein;

a switch electrically interconnected with said power means positioned for engagement with one end of said rod and adapted to be closed thereby, whereby said power means is caused to rotate in one direction when said switch is biased to a rst position by said rod and in the opposite direction when said switch is disengaged by said rod and moves to a second position; and

means on said rod adapted to engage said piston means to cause said rod to move longitudinally to close said switch and to engage said piston means to cause said rod to move in a relatively opposite direction opening said switch.

3. In a pump:

a housing having a pair of spaced cylinders therein;

piston means operably disposed in each of said cylinders and including:

a piston operably disposed in each of said cylinders;

a ball nut mounted on one end of each of said pistons;

a pair of rotatable shafts each having a threaded portion operably engaging the ball nut on one of said pistons whereby said pistons are caused to move in a linear direction in response to rotation of said rotatable shafts;

a pair of meshing` gears, one of said gears being iixed to each of said rotatable shafts and rotatable therewith;

power means for driving said rotatable shafts in rotation at a constant rotational speed and being further characterized as instantaneously reversible;

connecting means for rotatably connecting said power means with at least one of said shafts; and

switch means operably engageable with at least one of said piston means and connected with said power means, whereby said power means is caused torotate said driving means in one direction and then the other.

4. A pump comprising:

a housing having a cylinder therein;

rigid piston means reciprocably disposed in said cylinder;

a rotatable, threaded shaft coaxially aligned with said piston means and engageable therewith for advancing said piston means into said cylinder when said shaft is rotated in one direction, and for withdrawing said piston means from said cylinder when said shaft is rotated in the opposite direction;

movably mounted switch rod means positioned adjacent said piston means and engageable with said piston means at two different times during the stroke of said piston means, once during the movement of said piston means into said cylinder, and once during the retraction of said piston means from said cylinder, said switch rod melans including a rigid switch contacting portion movable in opposite directions in response to engagement of said switch rod means with said piston means;

a synchronous, constant speed, reversible electric motor drivingly connected to said threaded shaft for driving said shaft in rotation, said motor being characterized as substantiallyinstantaneously reversible; and

a two-position reversing switch connected in the power supply to said electric motor for effectively instantly reversing the direction of rotation of said motor when said reversing switch is thrown from one of its two positions to the other, said two-position reversing switch being positioned in the path of movement of said rigid switch contacting portion to be thrown periodically and alternately to its two positions as it is periodically engaged and disengaged by the rigid switch contacting portion of said switch rod means whereby said constant speed reversible electric motor is directly and substantially instantaneously reversed by the movement of said piston means in said cylinder, and at periodic intervals during the movement thereof.

5. A constant velocity and volume a housing having a pair of spaced therein;

valve means located in one end of said housing in fluid communication with said cylinders;

a first piston located partially in one of said cylinders and adapted for linear movement in said cylinder and having a longitudinally extending bore therein;

a second piston located partially in the other said cylinder andadapted for linear movement in said pump including: cylinders formed cylinder and having a longitudinally extending bore therein;

a ball nut mounted on the end of each of said pistons extending from said cylinders and arranged axially with respect to said bores;

a first rotatable shaft having threads thereon mating with the ball nut on said first piston and extending into the bore therein;

a second rotatable shaft having threads thereon mating with said ball nut on said second piston and extending into the bore therein;

a pair of meshing gears, one of said gears being iixed to each shaft and rotatable therewith, whereby said shafts are caused to rotate in relatively opposite directions;

power means operably connected with at least one of said shafts for rotating said shaft at a constant rotational speed, said power means further characterized as being instantaneously reversible; and,

switch means operably connected with said power means and` adapted for engagement with at least one of `said ball nuts, whereby said power means is caused to rotate said shafts in 'one direction and then the other.

6. The pump of claim 5 wherein said power means includes a synchronous electric motor further characterized as having a relatively low rotational speed; and,

connecting means rotatably connecting said. motor with at least one of said shafts, whereby said shaft is caused to rotate with said motor.

7. The pump of claim 6 wherein said connecting means includes:

includes:

a rod positioned in said housing for longitudinal movement therein;

a switch connected with said power means adapted to be moved from a first position to a second position by said rod whereby said power means is caused to rotate in one direction when said switch is in said first position and in the opposite direction when said switch is in the second position; and,

first and second projections on said rod adapted to be engaged with the ball nut on one of said pistons whereby said rod will be moved in one direction to move said switch to said rst position when said ball nut engages said first projection and will be moved in the opposite direction when said ball nut engages said second projection to move .said switch to said second position.

9. A constant velocity and volume pump including:

a housing having a pair of spaced cylinders formed therein;

valve means located in one end of said housing in fluid communication with said cylinders;

a lirst piston located partially in one of said cylinders and adapted for linear movement in said cylinder and having a longitudinally extending bore therein;

a second piston located partially in the other said cylinder and adapted for linear movement in said cylinder in a direction relatively opposite to said first piston and having a longitudinally extending bore therein;

sealing means located on each of said pistons sealingly engaging the housing surrounding said cylinders;

a ball nut mounted on the end of each of said pistons l 1 extending from said cylinders and arranged axially with respect to said bores; a first rotatable shaft having threads thereon mating with and extending throu-gh the ball nut on said rst cog-type pulley to rotate in response to rotation of said second cog-type pulley.

13. In the 4pump of claim 1t) and also including:

first valve means having an outlet in fluid communipiston into the bore therein; 5 cation with one of said cylinders adapted to control a second rotatable shaft having1 threads thereon mating the ow of a fluid out of said cylinder and an inlet with and extending through the ball nut on said adapted to control the flow of fluid into `said cylinder second piston into the bore therein; in response to the reciprocating movement of the a pair of meshing gears, one of said gears being fixed piston -means disposed therein; and,

to the unthreaded portion of each shaft and rotatsecond valve means in fluid co-mmunication with the able therewith, whereby said shafts are caused t0 other of said cylinders adapted to control the ow of rotate in relatively opposite directions; a fluid into and out of said cylinder in response to a first pulley mounted on one of said shafts; the `reciprocating movement of the piston means thereon and adapted to be rotated thereby, said syndisposed therein and havin-g an inlet in fluid comchronous motor being characterized as having a relamunication with the inlet in said rst valve means. tively slow constant speed and being instantaneously 14. A pump comprising: reversible; a housing having a large cylinder formed therein and a belt extending between said pulleys whereby said a small cylinder formed therein;

synchronous motor is adapted to rotate said first a large piston reciprocably disposed in said large cylpulley; inder and having a longitudinally extending bore a rod positioned for longitudinal movement in said therein;

housing; a small piston reciprocably disposed in said small cyla two-position switch electrically interconnected with inder rand having a longitudinally extending bore said synchronous motor arranged to engage said therein; rod, Said Switeh being arranged whereby Said fnotor a lball nut mounted on one end of 4said pistons and rotates in one direction when said switch is in one `axially aligned with said bores; Position and in the opposite direction when said a first rotatable shaft having threads theneon mating SWitCh iS in the other PoSition; and, with the ball nut fon said large piston and extending first and second projections on said rod adapted to into said bore;

engageone of Said bail nuts whereby when Said a second rotatable shaft having threads thereon matrst projection is in engagement therewith said rod is ing with the bali nut 0n said small piston and exmoved to move said switch t-o said one position and tending into Said bore; when Said Second Projection iS in engagement there' nrs-t yand second cog-type pulleys mounted on said rst with said rod is moved to move said switch to the Shaft; other position. 35 a third cog-type pulley mounted on said secon-d shaft; 10. In a pump: power means including:

a hoilSing haying a Pair of SPaeed Cylinders therein a synchronous electric motor characterized as pist-0n means Operabiy dispo-Sed in each 0f Said eyilnhaving a relatively new constant rotational ders and including a ball nut mounted on one end ,speed ,and as being substantially instantaneousof each said piston means; 40 .ly reversible, and rotatable driving means operably connected with each a fourth Cog-type pulley mounted on Said motor;

of Said PiStonS adapted to reciprocate Said PiStonS connecting means extending between said power means in said cylinders, said driving means including a and iii-st Shaft and including; rotatable Shaft for eaeh PiSton means 'having a a first cog-type belt tdrivingly connecting said rst threaded porti-on thereon engageable with said ball .and fourth pulleys, and nnte, whereby Said Piston means are Caused t0 move 45 a second cog-type belt drivingly connecting said in a linear direction in response to rotation of said Second `find third pulleys; and, shafts; switch means connected with said motor and includpower means for rotating said driving means at a coning;

4Stent rotational Speed and being further eharao- Ia rod slidingly positioned in said housing, i teliZCd aS inStantaneoilSiy reversible; a two-position switch connected with said power connecting means for rotatably connecting said power means `and adapted to be moved from a rst pomeans with `said shafts whereby said shafts are Sition to a second position 'by said rod whereby caused to rotate in the Same direction; and, said power means is caused to rotate in one di- SWitCh IneanS oPerabiy engageabie with at ieaSt one of rcction when said switch is in said first position Said Piston TneanS and Connected with Said `Power and in the opposite direction when said `switch means, whereby said power means is caused to roits in Said second position7 and tate said driving means in one direction and then first and second projections on Said rod adapted to the other. 'be engaged by one of said ball nuts whereby said In the Of Claim wherein Said POWCI' mSaIlS ,ford be moved in .one direction to move includes :a synchronous electric motor further charac- Said Switch to Said first position when said bail terized fas having `a relatively low rotational speed. D nut engages Said nist projection and will he 12. In the pump of claim 10 wherein said connectlng moved in the opposite `direction t0 move Said means includes: switch *to said second position when said ball `a first cog-type pulley mounted on one of said shafts; nut engages said Second projection. a second cog-type pulley mounted on the same one of 65 said shafts; References Cited by the Examiner a thirdcog-type pulley mounted on the other of said UNITED STATES PATENTS shafts; `a fourth cog-type pulley mounted on said motor; 532,561 5/97 TU mer et ab 103-170 a first cog-type belt mating with said rst and fourth 1,624,423 4/27 Milton 103-57 X pulleys and arranged to cause the .rotation of said 1,770,683 7/ 30 Davis 103-57 X =lirst cog-type pulley in response to rotation of said 2,368,131 1/45 French 1()3 57 X motor; and, 2,377,743 6/45 Ar-utunoff 103--57 X a second cog-type belt mating with said second and third cog-type pulleys arranged to cause said third ROBERT M. WALKER, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent Non 3,208,388 September 28, 1965 Clarence Oo Glasgow It is hereby certified that error appears in the above numbered patent requiring correct' corrected below.

Column ll, line l3 after "shafts;" insert synchronous moto a r having a secon d pulley mounted Signed and sealed this 31st day of May 1966.

(SEAL) Attest:

ERNEST W. SW1DER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. IN A PUMP: A HOUSING HAVING A PAIR OF SPACED CYLINDERS THEREIN; PISTON MEANS OPERABLY DISPOSED IN EACH OF SAID CYLINDERS AND INCLUDING: A PISTION RECIPROCABLY DISPOSED IN EACH OF SAID CYLINDERS; AND A BALL NUT MOUNTED ON AN END OF EACH OF SAID PISTONS; A PAIR OF ROTATABLE SHAFTS EACH AXIALLY ALIGNED WITH EACH OF SAID PISTONS AND HAVING A THREADED PORTION THEREON OPERABLY ENGAGING THE BALL NUT OF THE RESPECTIVE PISTON WHEREBY SAID BALL NUTS AND PISTONS ARE CAUSED TO MOVE IN A LINEAR DIRECTION IN RESPONSE TO ROTATION OF THE RESPECTIVE ROTATABLE SHAFT; POWER MEANS FOR DRIVING SAID ROTATABLE SHAFTS AT A CONSTANT ROTATIONAL SPEED AND BEING FURTHER CHARACTERIZED AS INSTANTANEOUSLY REVERSIBLE; CONNECTING MEANS FOR ROTATABLY CONNECTING SAID POWER MEANS WITH AT LEAST ONE OF SAID SHAFTS; AND SWITCH MEANS OPERABLY ENGAGED WITH AT LEAST ONE OF SAID PISTON MEANS AND CONNECTED WITH SAID POWER MEANS, WHEREBY SAID POWER MEANS IS CAUSED TO ROTATE SAID DRIVING MEANS IN ONE DIRECTION AND THEN THE OTHER. 